"According to the latest estimates, there are approximately 2,500 Russians and 7,000 CIS nationals," Sutormina said. The figures announced earlier by Marina Kochubey, chairperson of the Scientific Advisory Board at the Anti-Terrorist Center of CIS Member Countries, were based on the information from 2014. Kochubey said that from 800 to 1,500 Russian nationals are fighting alongside the extremist group in Iraq and Syria.

Sutormina said that IS recruiters pay special attention to remote "auls and villages where young people have no prospects."

The Islamic State is an extremist organization banned in Russia. In 2013-2014, it called itself the Islamic State of Iraq and the Levant (ISIL). In June 2014, IS announce the establishment of the "Islamic caliphate" on the territories seized in Iraq and Syria. According to US’ Central Intelligence Agency, the extremist group includes around 30,000 people, while Iraqi authorities claim there are around 200,000 in IS. Among members of the group are citizens of 80 countries, including France, Great Britain, Germany, Morocco, Saudi Arabia, US, Canada, as well as Russia and other CIS countries. According to reports, militants now control around 40% of the Iraqi territory and 50% of the Syrian territory.